This project will continue our investigation of amino acid and protein intake on metabolism during exercise and recovery in humans. Stable isotope tracer methods will be used to determine in vivo rates of urea production, intestinal mucosal protein synthesis, muscle protein synthesis, and amino acid appearance and oxidation. In separate arms of the study, we will focus on the response to insulin and/or intravenous amino acid supplementation at rest, during exercise, and during recovery from strenuous aerobic or resistance exercise.